1. Field of the Invention
The present invention relates to an electrical connection box and to its method of manufacture. Furthermore, the present invention relates to a wire connection busbar of an electrical connection box and its production method.
2. Description of the Related Art
A prior art electrical connection box, such as a junction box, contains branch circuits at high density. Wires and push-in terminals may be used singularly or together with a busbar to form circuits in the prior art electrical connection boxes. To accommodate the high density of circuits, wires are laid along the inner surfaces of the lower and upper casings of the electrical connection box. The busbar then is arranged with insulating plates provided between the busbar and the wires in the lower and upper casings. In other words, circuits accommodated in the prior art electrical connection box have a layered construction of the wires, the busbar and more wires.
A prior art electrical connection box, as described above, is manufactured as shown in FIG. 16 by placing a lower casing 1 and an upper casing 2 side by side on the same plane and spaced apart by a specified clearance C, such that the respective inner surfaces face upwardly. Connectors 3 and 4 are fixed by jigs or like devices in predetermined positions on the upwardly facing inner surfaces of the lower and upper casings 1 and 2, and push-in terminals 5 are mounted into terminal mount holes of the connectors 3 and 4. Each terminal 5 has an upwardly facing slot formed with a blade. A strand of wire (single core wire) w is laid between the lower and upper casings 1 and 2 over the clearance C, i.e. from the lower casing 1 to the upper casing 2 and then back from the upper casing 2 to the lower casing 1, and so on along the inner surfaces of the side by side lower and upper casings 1 and 2. The wire w is pushed directly into the slots of the push-in terminals 5 mounted in the connectors 3 and 4 of the lower and upper casings 1 and 2, thereby connecting the wire w and the push-in terminals 5. The upper casing 2 then is turned onto the lower casing 1 as indicated by an arrow in FIG. 16. In particular, the upper casing 2 is fitted to the lower casing 1 in such a way that the wire w in the lower casing 1 faces the wire w in the upper casing 2.
The lower casing 1 to be fitted to the upper casing 2 may be constructed as shown in FIG. 17. Specifically, an insulating plate 6 is placed on a circuit formed by the wire w and the push-in terminals 5. A busbar 7 then is placed thereon, and an insulating plate 8 is further placed on the upper surface of the busbar 7. The lower casing 1 then is fitted to the upper casing 2 to arrange the wire w in the upper casing 2.
Since the wire w is laid with the lower and upper casings 1 and 2 placed on the same plane as described above, it should be laid over the clearance C defined between the lower and upper casings 1 and 2. If an attempt is made to fit the lower and upper casings 1 and 2 to each other in this state, a wire portion w-a extends over the clearance C between the lower and upper casings 1 and 2 and must be folded into a U-shape like a hinge as shown in FIG. 22. This wire portion w-a bulges outwardly and causes a problem.
The busbar 7 may have tabs 7a that project in positions near the side of the upper casing 2 toward the lower casing 1. In such a case, when the lower and upper casings 1 and 2 are rotated to each other, the tabs 7a of the busbar 7 may not align properly for insertion into specified mount holes formed in the upper casing 2.
The present invention was developed in view of the above problems, and an object thereof is to prevent a wire from bulging out from an outer surface at one side of a fitting portion of lower and upper casings and to solve a problem that tabs cannot be properly inserted into mount holes of the upper casing when the upper casing is fitted to the lower casing by being turned onto it.